Three li'l pigs and the hunt for blood substitutes
Article Abstract:
For nearly 50 years, scientists have been trying to synthesize a human blood substitute, which would attach to oxygen in the lungs and carry and release the oxygen to the tissues of the body. Transgenic pigs (pigs that have received a foreign gene during their embryonic development) have been genetically engineered to produce human hemoglobin, the oxygen-carrying pigment in red blood cells. DNX, Inc., a biotechnology firm in Princeton, New Jersey, has produced three transgenic pigs. However, a number of obstacles must be overcome before the product can be used as a substitute for blood in humans. Scientists have previously shown that the hemoglobin molecule by itself, outside of the red blood cell, binds to oxygen but can not release it to the tissues. In addition, by itself, the hemoglobin molecule readily breaks down and causes kidney damage when it is filtered out of the blood. Other companies have chemically crosslinked hemoglobin molecules to overcome these problems. However, trials of these chemically-modified hemoglobin molecules have not been successful, as toxic side effects have developed in individuals injected with them. It is not certain if the hemoglobin made in the transgenic pigs will be any better, as it also has to be chemically modified. Scientists are developing modified hemoglobin genes so that these chemical changes will occur naturally in the pigs. This type of genetic engineering has already been achieved in hemoglobin genes expressed in bacteria and yeast. Further study will show if these genetically engineered hemoglobin molecules can be used as blood substitutes in humans. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1991
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Biogeographers take a new view of the ancient Andes
Article Abstract:
Ancient fish and bird fossils from the South American Andes suggest that the region underwent geological transformations earlier than previously thought. The new belief among scientists is that the Andes are a complex mountain structure that were shaped by tectonic movements at different times.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1996
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Moving forest trees into the modern genetics era
Article Abstract:
The timber industry industry is centuries behind the rest of agriculture in the science of breeding. New gene-mapping information may lay the foundation for breeding trees for desirable traits by conventional breeding or gene-transfer techniques.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1996
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